Copper-Catalyzed Allylic Alkylation of Trisubstituted Vinylaluminum Reagents

Significance

Vinylaluminum reagents, accessible through hydroalumination of alkynes with DIBAL-H, can be valuable nucleophiles and coupling partners. The authors report the use of silylprotected alkynes giving both E- and Z-alkenes; an improvement on the group’s previous work where only E-vinylaluminum reagents could be generated (J. Am. Chem. Soc. 2008, 130, 446). The vinylaluminum reagents are then alkylated with allylic phosphates using an NHC-copper catalyst (see Review below). High enantio- and ­regioselectivity is achieved with retention of the alkene stereochemistry. This methodology is used in the first enantioselective synthesis of nyasol.

Review: C. A. Falciola, A. Alexakis Eur. J. Org. Chem. 2008, 3765-3780.